Automatic handler for feeding containers into and out of an analytical instrument

ABSTRACT

An analytical instrument has a sample handler for inputting racks of containers, including various types and sizes of test tubes, both capped and uncapped, and inserts, into the instrument. The sample handler has an infeed, an outfeed and a cross-feed between the infeed and outfeed. The infeed and outfeed advance the racks of containers using walking beam mechanisms which lift the racks by tabs on the right and left sides of the rack, which are positioned at a substantially identical height. Racks input into the infeed are transferred by the walking beam mechanism to a track on the cross-feed. They are then pushed, by a transport subassembly having a platform with pivotable pusher fingers to cam the rack and to push it in only one direction, from behind the infeed to a fixed position behind the outfeed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the following U.S. patent applications,having the indicated titles, commonly assigned to the Bayer Corporationof Tarrytown, N.Y. and incorporated by reference herein:

(a) design patent applications for Gripper Finger, Ser. No. 29/090,683,filed concurrently herewith; Sample Tube Rack, Ser. No. 29/090,547,filed Jul. 10, 1998; and Sample Tube Rack, Ser. No. 29/089,359, filedJun. 15, 1998;

(b) utility patent applications for Sample Tube Rack, Ser. No.09/113,643, filed Jul. 10, 1998; Sample Tube Rack, Ser. No. 09/097,790,filed Jun. 15, 1998; Reagent Package, Ser. No. 08/985,759, filed Dec. 5,1997; Diluent Package, Ser. No. 29/088,045, filed May 14, 1998; DynamicNoninvasive Detection of Analytical Container Features Using Ultrasound,Ser. No. 09/115,393, filed concurrently herewith; Robotics forTransporting Containers and Objects Within an Automated AnalyticalInstrument and Service Tool for Servicing Robotics, Ser. No. 09/115,080,filed concurrently herewith; Automatic Decapper, Ser. No. 09/115,777,filed concurrently herewith; and Stat Shuttle Adapter and TransportDevice, Ser. No. 09/113,640, filed Jul. 10, 1998.

FIELD OF THE INVENTION

This application relates to an automated sample handler for ananalytical instrument in which racks holding capped or uncapped testtubes or other containers are input into and output from the instrument.

BACKGROUND OF THE INVENTION

Many different types of sample handlers have been used in variousanalytical instruments to feed multiple test tubes into and out of theinstrument. Several manufacturers have utilized a sample handler systemwhereby the sample handler comprises an input queue, an output queue anda cross-feed. The input queue consists of an area in which racks of testtubes are input into the instrument and are transported toward thecross-feed. The racks are then transferred to the cross-feed, where oneor more racks may be at a given time. The racks are indexed at setpositions along the cross-feed where operations are performed on thetest tubes, such as aspirating samples from the test tubes, and theracks are then moved to the end of the cross-feed adjacent the outputqueue where they are output to the output queue. One such system isdescribed in U.S. Pat. No. 5,207,986. Various methods are used totransport the racks within the input queue and output queue. In someinstruments, like the Chem I system sold by the Bayer Corporation, theinput queue and output queue are indexed and walking beams are used tolift the base of the racks and translate them from one indexed positionto an adjacent indexed position.

It is desirable to provide a sample handler that handles containers ofvarious types, diameters and heights, whether capped or uncapped, and topermit a robotic arm to transport the containers to and from the samplehandler for faster processing elsewhere without have to return thecontainers to a particular rack or position on the rack.

These prior art instruments do not provide this flexibility. First, theyonly handle a single type and style of test tube within a particularinstrument. Second, these sample handlers are not designed to work inconjunction with a robot that removes containers, such as test tubes,individually from the racks for transport either within the instrumentor between the instrument and a laboratory automation transport line. Anentire rack would likely be lifted if a robot were to attempt to lift atest tube from a rack in the prior art instruments. Third, the inputqueue and output queue generally are not designed to handle uncappedtest tubes because they do not stabilize the racks sufficiently andsamples in open test tubes may spill. Fourth, the positions of the testtubes within a particular rack must be maintained or the instrumentswill be unable to track and perform the proper operations on the testtubes.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an automated handler forfeeding test tube racks, which may hold capped or uncapped test tubes,into an analytical instrument and output uncapped test tubes (alsoreferred to as “open test tubes”) from the instrument after the contentsof the test tubes have been sampled.

It is a further object of this invention to provide an automated handlerfrom which individual test tubes and other containers can be retrievedfrom racks and returned to racks individually by a robotic arm.

It is a further object of this invention to provide an automated handlerfor an analytical instrument that is operable in either a free standingmode, in which racks of test tubes are manually inserted into andremoved from the handler, or as a subsystem in a laboratory automationsystem in which test tubes are retrieved from or returned to a transportline containing test tubes.

A first aspect of the present invention is directed to a sample handlerfor an analytical instrument having a feeder for handling a rack, whichmay hold containers. The feeder comprises left and right side walls of asubstantially identical height, a walking beam mechanism, and a tray,having walls of a substantially identical height, that is moved by thewalking beam mechanism. When the walking beam mechanism is activated,the tray lifts a rack, which has tabs on the left and right side of therack at a substantially identical height, from the side walls of thefeeder. The feeder may be an infeed or an outfeed of a sample handler.The tray in the feeder has asymmetric guide rails to prevent the rackfrom skewing in the tray.

Another aspect of the present invention is directed toward an analyticalinstrument having a sample handler that interacts with a robotic arm onthe instrument. The sample handler has an infeed, cross-feed andoutfeed. A rack is input to the instrument in the infeed and is thentransferred to a track on a cross-feed of the sample handler. Pusherfingers beneath the track push the rack from behind the infeed toanother position, preferably behind the outfeed, where the robotic armremoves containers for transport elsewhere in the instrument. Anultrasonic range sensor detects whether a rack has been inserted intothe infeed and whether the rack is skewed when it is placed on thecross-feed track behind the infeed. A reader of machine-readable code,such as a bar code reader, and an ultrasonic liquid level sensor arepositioned adjacent the track to identify the container and profile thecontainers before the robotic arm removes the containers from the rack.

Another aspect of the present invention is directed to a sample handlerhaving an outfeed with a walking beam mechanism to move the racks with amovable tray. A rear area of the tray has side walls that have aplurality of detents separated by ridges to capture a rack within thedetents and hold the rack in a fixed position for the return ofcontainers to the racks.

Another aspect of the present invention is directed toward a samplehandler having an infeed, cross-feed, outfeed, and stat shuttle. Thestat shuttle provides for the inputting of containers on a prioritybasis, including containers that may otherwise be input on a rack placedin the infeed. The stat shuttle also permits the inputting andoutputting of a variety of containers. Like the cross-feed, the statshuttle has a bar code reader and ultrasonic liquid level sensor toidentify and profile containers in the stat shuttle. Thus, containersthat are unidentified or not properly profiled in the cross-feed may betransferred to the stat shuttle for another attempt at identificationand profiling.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventions and modifications thereof will become better evident fromthe detailed description below in conjunction with the following figuresin which like reference characters refer to like elements in which:

FIG. 1A is a perspective view of the sample handler of the presentinvention for an analytical instrument and some adjacent components ofthe instrument with several panels and doors of the instrument situatedabove the sample handler;

FIG. 1B is a top view of the sample handler of FIG. 1A;

FIG. 1C is a perspective view of the sample handler of FIG. 1A withoutthe panels and doors of the instrument situated above the samplehandler;

FIG. 2A is a perspective view of the bottom of the test tube rack;

FIG. 2B is an elevational view of the rack holding test tubes and of thepusher fingers, shown in dotted lines, positioned within openings on thebottom of the rack after the rack is placed onto the cross-feed trackbehind the infeed;

FIG. 3A is a perspective view of portions of the infeed and cross-feedof the sample handler with a test tube rack in a frontoperator-accessible area;

FIG. 3B is a perspective view of portions of the infeed and cross-feedwith a test tube rack in a rear area of the infeed that is notaccessible to the operator;

FIG. 3C is a perspective view of portions of the infeed and cross-feedwith the test tube rack positioned in the infeed end of the cross-feed;

FIG. 3D is a perspective view of portions of the outfeed and cross-feedwith the test tube rack positioned in the outfeed end of the cross-feed;

FIG. 3E is a perspective view of portions of the outfeed and cross-feedwith the test tube rack positioned in the rear area of the outfeed whichis inaccessible to an operator;

FIG. 3F is a perspective view of portions of the outfeed and cross-feedwith the test tube rack positioned in the forward-most position in therear area of the outfeed with tabs on the rack positioned under clampsthat are in their open position;

FIG. 4A is a top view of the infeed with the tray removed;

FIG. 4B is a perspective view of the walking beam mechanism and severalcross-beams of the infeed attached to only the right wall of infeed, thewalking beam mechanism of the outfeed being similar;

FIG. 4C is a cross-sectional view along line C—C of FIG. 4B of theslider block of the walking beam mechanism with a shoulder screw ofinfeed tray, shown in FIG. 5C, rested within a channel of the sliderblock;

FIG. 5A is a top view of infeed tray;

FIG. 5B is a side view of infeed tray;

FIG. 5C is a cross-sectional view of a portion of the infeed tray alongline C—C of FIG. 5B;

FIG. 6A is front view of the cross-feed;

FIG. 6B is a perspective view of the cross-feed from the rear of thecross-feed;

FIG. 6C is a perspective view of the cross-feed of FIG. 6B from the rearof the cross-feed with the main floor, rear wall, rack endstop, mountbracket and track removed;

FIG. 6D is a perspective view of the cross-feed of FIG. 6C with thefront wall removed;

FIG. 6E is a front perspective view of the cross-feed with theultrasonic liquid level sensor positioned above a rack with containers;

FIG. 6F is a perspective view of the gimbal in which the ultrasonicliquid level sensor is mounted;

FIG. 6G is a perspective view of the sensor holder to which the gimbalis mounted;

FIG. 6H is a perspective view of the platform;

FIG. 7A is a top view of the outfeed tray;

FIG. 7B is a side view of the outfeed tray;

FIG. 7C is a cross-sectional view of a portion of the outfeed tray alongline C—C of FIG. 7B;

FIG. 8A is a front isometric view of the laboratory automation adapter;

FIG. 8B is an exploded view of the laboratory automation adapter of FIG.8A;

FIG. 9 is an isometric view of a stat shuttle that may included in thesample handler;

FIG. 10A is a side elevational view of the cam profile for the infeedwalking beam mechanism; and

FIG. 10B is a side elevational view of the cam profile for the outfeedwalking beam mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, an analytical instrument 10 has a samplehandler 20 according to the present invention to input and outputcontainers to instrument 10. Sample handler 20 comprises an infeed (or“input queue”) 80, a cross-feed 95, and an outfeed 100 (or “outputqueue”). Infeed 80 and outfeed 100 are positioned parallel to oneanother along their length. Cross-feed 95 is positioned behind infeed 80and outfeed 100 and extends at least from behind the leftmost wall ofinfeed 80 to behind the rightmost wall of outfeed 100.

Instrument 10 has one or more modules (not shown) in addition to samplehandler 20 to perform various operations, including analyses, on thecontents of a test tube. Various panels 30, 40, including doors 35, 45and a tower 50 for electronic controls are positioned above samplehandler 20 and prevent access by an operator to the rear of samplehandler 20, including a rear area 82 of infeed 80 and the rear area 102of outfeed 100 as well as the entire cross-feed 95 during operation ofthe sample handler. If doors 35 or 40 are opened, sample handler 20 (andone or more robotic arms that may interact with the sample handler)stops. The operator may access a front area 81 of infeed 80 and a frontarea 101 of outfeed 100, however, while instrument 10 is operating.

Multiple microcontrollers control the operation of instrument 10 andcommunicate with one another over a CAN bus. One of these controllers isa sample handler controller, which may comprise a control board based onthe Intel 386EX microprocessor. Sample handler controller communicateswith and serves as a master controller for a separate controller forcross-feed 95 as well as separate controllers for the robotics whichoperate in conjunction with sample handler 20. Cross-feed 95 may be aCAN node and the cross-feed controller may comprise a Phillips 8051microprocessor to control the high current stepper motor of cross-feed95. Software in the sample handler controller provides a user interfaceto permit the user to control various aspects of sample handler 20.

Preferably, in order to save on processing time by the controllers, agrid of all of the potential “registration locations” from and to whicha container may be moved is mapped out in workstation software beforeinstrument 10 is first activated. In the disclosed embodiment, theseregistration locations include eight locations in the outfeed side ofcross-feed 95, one location per tube receptacle 66 on one of racks 60,and 72 locations in rear area 102 of outfeed 100, including 8 possibletube receptacle locations on each of 9 possible racks in rear area 102.

A control keypad is incorporated into tower 50 on the front of samplehandler to permit the operator to stop the motion of infeed 80,cross-feed 90, or outfeed 100 in the event of a jam or to clean a spill.

Test Tube Racks

Test tubes or inserts, such as Microtainers®, or tubes with Ezee-Nest®inserts (generically referred to below as “test tubes”) are placed intotest tube racks 60 (FIG. 2B) designed specifically for transporting thetest tubes through sample handler 20. A bar code label 70, or some otherform of machine-readable identification code, is affixed to each ofracks 60 and, similarly, a bar code label 71, or some other form ofmachine-readable identification code, is affixed to each test tube toallow instrument 10 to identify the racks 60 and test tubes and are usedto identify, through a work order generally entered by the operator atthe workstation or downloaded from a hospital laboratory system, whatmust be done with the test tubes. Custom-designed racks 60 are thesubject of the referenced application assigned Internal Docket No.:MST-2302.

Each of racks 60 may hold as many as eight test tubes, which may be testtubes of various types, heights, and diameters, in individual tubereceptacles 66 separated by side walls 64. A lateral front wall 61 eachrack has openings 63 in front of each test tube location that aresufficiently large to expose the bar code label 71 on each test tube tobe read by a bar code reader 55 (FIG. 1B) (or, if a machine readableidentification code other than bar codes are used, a device suitable forreading that code) while a lateral rear wall 65 of each rack is closed.Test tubes are placed in the rack 60 by the operator and held in placewith a spring, preferably a vertical leaf spring 67, in each tubereceptacle 66. The test tubes must be firmly seated in the tubereceptacles 66 to hold the test tubes securely, to prevent collisions ofan improperly seated test tube with various obstructions (such as panel30), and to provide precise positioning of the test tubes to permit barcode reader 55 to identify each test tube and an ultrasonic liquid levelsensor 90 to determine the level of liquid therein and to detect thepresence of caps on test tubes.

Tabs 110, 111 (or “ears”) on each side of racks 60 are located at thesame height on each side of racks 60 and are used to hold racks 60upright and to lift and advance the position of rack 60 in infeed 80 andoutfeed 100 as explained below. Tabs 110, 111 are also used by sensors92, 93 (FIGS. 3A and 3E) in cross-feed 95 to detect the presence of arack 60 at either side of cross-feed 95 and to provide a reference levelfor profiling by ultrasonic liquid level sensor 90. Recesses 115, 116 oneach of respective tabs 110, 111 are provided to allow a pair of clamps103, 104 in outfeed 100 to hold rack 60 in place.

Two openings 68, 69 are provided at the bottom of racks 60 (FIG. 2A) forracks 60 to travel over guide rails 130, 131 on infeed tray 120 asfurther described below. Openings 68, 69 in the bottom of racks 60 havea width W sufficient to fit pusher fingers 94 a, 94 b within openings68, 69 with the pusher fingers in the raised position without contactingthe rack and to prevent the rack from camming on guide rails 130, 131 ontray 120 and guide rails 500, 501 on outfeed 100 (as indicated by pusherfingers shown as dotted lines in FIG. 2B). On the right side of eachopening is a respective window 72, 74 to be engaged by respective pusherfingers 94 a, 94 b (FIG. 6C) on cross-feed 95. On the left side of andcontinuous with openings 68, 69 are internal voids 76, 78 that providethe additional clearance necessary for fingers 94 a, 94 b to firstdisengage from windows 72, 74 before being pivoted downward to the rightas the platform 410 to which they are attached moves to the left ofcross-feed track 336 (described below) when pusher fingers 94 a, 94 bhit respective walls 79 a, 79 b on racks 60. Openings 68, 69 arepositioned asymmetrically along the length of the rack 60 (as are guiderails 130, 131 in infeed tray 120) to intuitively guide the operator toinsert racks 60 into infeed 80 in only one direction with the front wall61 of racks 60, the bar code labels 70, 71 on racks 60 and test tubes,respectively, facing the front of infeed 80 to be read by bar codereader 55 on cross-feed 95.

A ballast (not shown) weighing approximately 35-40 grams is incorporatedwithin each of racks 60 during assembly and is located between windows72, 74 to stabilize racks 60.

The movement of racks 60 within sample handler 20 will be described indetail below.

Infeed

An operator inserts test tubes into racks 60 and inserts racks 60 intoinfeed 80. Infeed 80 holds multiple racks, each of which may contain oneor more test tubes or, in one particular situation to be explained, mayintentionally contain no test tubes. In a preferred embodiment, infeed80 holds as many as 21 racks.

Infeed 80 uses a bidirectional “walking beam” mechanism mounted above achassis 57 (FIG. 1A) to move racks within infeed 80 and outfeed 100 andto move racks 60 to and from cross-feed 95. The walking beam mechanismis somewhat similar to the mechanism for moving racks 60 in input andoutput queues as described in U.S. application Ser. No. 08/822,585,filed Mar. 20, 1997 and commonly assigned to the Bayer Corporation,which is incorporated by reference herein. However, among variousdifferences, in infeed 80 of the present invention, the walking beammechanism has walking beams that are of substantially equal height tostabilize racks 60. Moreover, in the present invention, the walking beammechanism moves racks 60 generally to the rear of infeed 80, rather thanto the front, by moving infeed tray 120, in which racks 60 are placed,sequentially in an upward motion, followed by a rearward motion, adownward motion and a forward motion.

FIG. 4A illustrates infeed 80 with infeed tray 120 removed. Infeed 80comprises two parallel side walls 121, 122 connected together withcross-beams, such as beams 123-126. Side walls 121, 122 are of equalheight so that tabs 110 on racks 60 may hang from the top rims ofrespective side walls 121, 122. Infeed 80 has no front and rear walls topermit easy insertion of racks 60 into infeed 80 and the transfer ofracks 60 to cross-feed 95. A drip tray 140 is attached to the front ofinfeed 80 to catch spills. (FIG. 1B)

Referring to FIGS. 5A-5C, infeed tray 120 is a movable tray placed ininfeed 80. Tray 120 has a bottom 150 and side walls 151, 152 (the“walking beams”) but is open at its front and rear like infeed 80 so asnot to obstruct the front and rear openings of infeed 80. A middlesection 153 on the rear of each of side walls 151, 152 slopes toward thefront of tray 120 and the bottom section 154 of side walls 151, 152 thendrops vertically to meet bottom 150. Thus, the tops of side walls 151,152 extend above cross-feed 95 as tray 120 moves rearward abovecross-feed 95 without tray 120 hitting cross-feed 95. This also resultsin the rearmost racks in tray 120 not being positioned above the bottom150 of tray 120 as they reach the back of tray 120. A short lip 155projects upward at the rear of tray 120 to contain spills withoutimpeding the movement of racks 60 out of the rear of infeed 80 and adrip tray 156 is attached to the front of tray 120.

Side walls 151, 152 are slightly lower, by approximately 1½ mm in thepreferred embodiment, than, and do not overlap the tops of, side walls121, 122 of infeed 80 when the walking beam mechanism is in the homeposition. The width of infeed 80 and tray 120 must be somewhat largerthan the width of racks 60 such that some skewing of the racks 60 willnot cause racks 60 to cam between side walls 151, 152 of tray 120. AU-shaped bracket 160 is mounted to the bottom of tray 120 and a shoulderscrew 165 is mounted within bracket 160.

Two stationary guide rails 130, 131 run from the front to the back oftray 120. Guide rails 130, 131 are each narrower than openings 68, 69 onracks 60 to allow openings to move over guide rails 130, 131. Racks 60do not actually sit on guide rails 130, 131 or on the bottom of tray 120but rather, as indicated above, are suspended above the bottom of tray120, hanging from tabs 110, 111 which rest either on the top of sidewalls 151, 152 of tray 120 or on the top of side walls of infeed 121,122. Openings 68, 69 on racks 60 key with guide rails 130, 131 to guideracks 60 along infeed 80 while preventing them from skewing or twistingmore than slightly within infeed 80. Openings 68, 69 leave adequateclearance for racks 60 to pass over guide rails 130, 131 to permit someskewing so the operator does not have to insert racks 60 into infeed 80with extreme precision. These features on tray 120 and racks 60 aresignificant because racks 60 may contain uncapped test tubes whosecontents may spill if racks 60 were not prevented from falling down intotray 120.

As explained above, guide rails 130, 131 are situated asymmetricallyalong the width of tray 120 to insure that racks 60 may only be insertedinto infeed 80 in a proper orientation with front wall 61 of each ofracks 60 facing the operator to expose bar code labels 70, 71 of racks60 and each test tube on racks 60 to bar code reader 55. As a result,the operator is intuitively guided by guide rails 130, 131 to not insertracks 60 in the reverse orientation. The top rims of side walls 151, 152of tray 120 are smooth so that the operator may slide racks 60 freelytowards the back of infeed 80 or toward the front of infeed 80 whenracks 60 are still in front area 81 which is accessible to the operator.

The walking beam mechanism is shown in FIG. 4B with tray 120 removed andwith various other components, including right wall 122 of infeed 80 andcross-beam 123, cut away to show more clearly how the walking beammechanism operates. A first lift bar 170 is mounted toward the rear ofinfeed 80. Lift bar 170 comprises a rod 172, the ends of which sit inholes in each of side walls 121, 122 and which defines a first pivotaxis around which lift bar 170 pivots, an I-shaped bar 174 and a secondrod 176 to which three rollers 177, one roller adjacent each end ofI-shaped bar 174 and one roller midway between the ends of I-shaped bar174, are mounted. A plastic tubular spacer 173 surrounds second rod 176and keeps rollers 177 spaced at the desired intervals. Second rod 176may move up and down in a slot 178 on each of side walls. (Only slot 178on left wall 121 is shown but the slot on right wall 122 is identical.)A third rod 179 is connected between a bracket 180 on the bottom of liftbar 170. A roller 182 is mounted to third rod 179 below the pivot axisof lift bar 170.

A second lift bar 190 is mounted toward the front of infeed 80. Thislift bar 190 also comprises a rod 192, the ends of which sit in holes ineach of side walls 120, 121 and which defines a second pivot axis aroundwhich second lift bar 190 pivots, an I-shaped bar 194 and a second rod196 to which three rollers 197, one adjacent each end of I-shaped bar194 and one midway between the ends of I-shaped bar 194, are mounted. Asecond plastic tubular spacer 193 surrounds second rod 196 and keepsrollers 197 spaced at the desired intervals. Second rod 196 may move upand down in a slot 198 on each of side walls 121, 122. (Only the slot onleft side wall 121 is illustrated.) A third rod 199 is connected betweenbracket 200 on the bottom of second lift bar 190 but no roller ismounted to third rod 199. A long link 230 serves as a tie rod connectingthird rod 199 on front lift block 190 to third rod 179 on rear liftblock 170, thereby driving second lift bar 190 in synchronization withfirst lift bar 170.

A motor 210, preferably a single gear brushless DC motor, is mounted infront of rear lift bar 170. Motor 210 has integrated control electronicsthat interface to the sample handler controller. A disk cam 220, havinga profile as shown in FIG. 10A, is mounted to a drive shaft on motor 210at the center of cam 220. Cam 220 is coupled to roller follower 182 onlift bar 170.

A slider block 240 slides above long link 230 and is trapped around longlink 230 with a keeper plate 250 mounted to slider block 240 beneathlong link 230 (FIG. 4C). One end of a second, shorter link 260 mounts tothe left side of slider block 240, generally toward the rear of sliderblock 240 to minimize the length of short link 260 and not interferewith the placement of tray 120 within infeed 80 by the pulling sliderblock 240 rearward over long link 230. Where sample handler 20 isdesigned to accommodate racks 60 according to the preferred embodiment,in which racks may be moved 25 mm per cycle of the walking beammechanism, the opposite end of short link 260 mounts to the right sideof cam 220 at a point 12½ mm away from the center of cam 220 so as tocause tray 120 to advance 25 mm toward the rear of infeed 80 with a 180°turn of cam 220. The precise amount of rearward movement of racks 60caused by each rotation of cam 220 is not significant in infeed 80 aslong as racks 60 move relatively quickly toward the rear of infeed 10.

A channel 270 running sideways through the center of slider block 240provides a means for locating tray 120 within infeed 80 by insertingshoulder screw 165 into channel 270. U-shaped bracket 160 fits aroundthe sides of slider block 240 and helps to locate and stabilize tray120. When tray 120 is inserted in infeed 80, with the walking beammechanism turned off, the top of side walls 151, 152 of tray sitpreferably 1½ mm below the top of side walls 121, 122 on infeed 80.

With tray 120 positioned within infeed 80 and sitting in its properposition on slider block 240, the operator may place one or more ofracks 60 into infeed 80. A long-range ultrasonic sensor 280 ispositioned on cross-feed 95 behind infeed 80. Range sensor 280 emitsultrasonic waves that travel toward the front of infeed 80. Racks 60 aremade from a material that reflects an echo back toward range sensor 280if racks 60 are inserted into infeed tray 120. An emitted wave that isreflected back to and detected by range sensor 280 as an echo signalsthat one or more racks are in tray 120.

Range sensor 280 may point directly toward the front of infeed 80 butdoes not in the preferred embodiment because it may be desirable toposition other components of instrument 10 behind cross-feed 95 andbecause it is desirable to also use range sensor as a skew sensor aswell to determine if the right side of a rack has been placed oncross-feed 90 skewed away from sensor 280. Therefore, in the preferredembodiment, range sensor 280 is positioned sideways along the axis ofcross-feed 95 pointing toward outfeed 100 and into a custom-designedacoustic mirror 290 which is mounted to the back wall 332 of cross-feed95 and which is off-center to the right side of infeed 80. Acousticmirror 290, a plastic passive reflector, is constructed frompolycarbonate, or any plastic that has a reflective surface.

A preferred range sensor 290 is manufactured by Cosense Sensors Inc. ofHauppauge, N.Y. as Model No. 123-10002. That sensor is enclosed in ashielded body that is 0.425″ diameter by 0.75″ long. Where the sensoremits a wave at a preferred frequency of 0.5 MHz for 150 milliseconds tohave a sufficient range to detect racks 60 inserted at the front ofinfeed 80, the dead zone, which equals the distance from sensor 280 inwhich the 0.5 MHz wave cannot be sensed is approximately 2 inches. (Thelength of the dead zone equals the distance the wave travels beforerange sensor 280 resumes listening for an echo from the wave.)Therefore, acoustic mirror 290 is approximately 2.5 inches long in thepreferred embodiment. The leftmost 2 inches 292 of acoustic mirror 290accounts for the dead zone within which movement directly withinacoustic mirror 290 in front of range sensor 280 cannot be detected. A0.5 inch angled portion 294 on the right of acoustic mirror 290 has areflective surface which is angled at a 45° angle toward the front ofinfeed 80. This bends by 90° the wave emitted by sensor 280 after it haspassed the dead zone and focuses the wave toward the front of infeed todetect the presence of racks in tray 120.

In order to best detect a skew of the right side of a rack in cross-feed90 while performing range sensing, acoustic mirror 290 should be mountedon cross-feed 90 behind infeed 80 with a bias to the right side ofinfeed as much as possible but the angled portion 294 should bepositioned so as to reflect wave toward the front of infeed 80 betweenguide rails 130, 131.

Software in instrument 10 may determine the distance of the object fromthe rear of cross-feed 95 based on the time it takes for the sound to bereflected back to range sensor 280. However, there is no need for thesoftware to track the precise position at which the rack that triggersthe walking beam mechanism is inserted, although software could beincluded to determine this information. If range sensor 280 isconfigured and operated to detect objects beyond the front of infeed 80,the software may also be programmed to reject signals detected by sensor280 that are generated by objects more than a certain maximum distancefrom acoustic mirror 290, such as a person walking in front of theinfeed 80, to prevent the activation of the walking beam mechanism bysignals outside of infeed 80.

The walking beam mechanism is activated by the detection by range sensor280 of racks 60 in infeed 80, unless there is a rack in the infeed sideof cross-feed 95. Upon activation of the walking beam mechanism, cam 220begins rotating and rolling against roller follower 182, causing liftbar 170 to pivot about rod 179 with rod 176 moving upward within slot178. Because front lift bar 190 is linked to rear lift bar 170 via longlink 230, the pivoting of rear lift bar 170 also causes front lift bar190 to pivot in the same direction. This causes tray 120 to move upwarda total of 3 mm with the top of side walls 121, 122 of tray 120 raised1½ mm above the top of side walls 151, 152 of infeed 80 when tray 120 isfully raised. As tray 120 moves upwards, tabs 110 on each of racks 60are picked up off the top of side walls 121, 122 of infeed 80 andtransferred onto the top of side walls 151, 152 on tray 120. In theevent that range sensor 280 fails and does not activate the walking beammechanism, the walking beam mechanism may be manually activated. Thespeed at which the walking beam is preferably activated is 25 rpm+/−2rpm. This speed, as well as the lift of cam 220 is selected to minimizethe noise generated by the transfer of racks 60 between side walls 121,122 and side walls 151, 152. The position of the walking beam mechanismfor infeed 80 (and for outfeed 100) is controlled by activating motor210 for a given time at a known speed.

As tray 120 nears completion of its upward motion and after racks 60have been transferred to the top of side walls 151, 152 on tray 120,short link 260 pulls slider block 240 rearwards, as provided for by thepositioning of the mounting of short link 260 to cam 260, thereby movingtray 120 with racks 60 rearwards approximately 25 mm. Cam 220 beginslowering lift bars 170, 190 as tray 120 nears completion of its rearwardmovement, thereby lowering tray 120. As the top of side walls 151, 152of tray 120 move below the top of side walls 121, 122 of infeed 80, tabs80 on racks 60 are again transferred from being supported on the top ofside walls 151, 152 of tray 120 to the top of side walls 121, 122 ofinfeed 80. As tray 120 is lowered, cam 220 causes slider block 240 tomove tray 120 toward the rear of infeed 80 approximately 25 mm to returntray 120 to its original position. As long as the walking beam mechanismis activated, tray 120 continues moving in accordance with theup-rear-down-forward directions with racks 60 being passed back andforth between the top of side walls 121, 122 and the top of side walls151, 152. This multidirectional motion of tray 120 causes racks 60 tomove rearwards in infeed 80, with some racks 60 pushing the racks 60behind them backwards toward cross-feed 95 to compact the racks 60 inthe rear of infeed 80. Thus, even if racks 60 were placed into tray 120somewhat skewed, the compacting motion will make them parallel to sidewalls 151, 152 of infeed tray 120.

Vertical panel 30 covering the front of instrument 10 is positionedabove infeed 80 and extends downward to limit operator access to reararea 82 of infeed 80. Panel 30 provides clearance for the tallest testtubes with the tallest caps which are properly seated in racks 60 andgives a visual cue to the operator to reseat any improperly seated testtubes. Infeed 80 has a front area 81 in front of panel 30 which isaccessible to the operator and, although rear area 82 is not accessibleto the operator, the operator could push racks 60 in front area 81toward rear area 82, causing racks 60 in rear area to be pushedbackward. The operator may remove a rack 60 or shuffle the order ofracks 60 before they pass behind panel 30 above infeed 80.

Test tubes on racks 60 must be seated properly in racks 60 by theoperator not only to insure the stability of the test tubes but also toposition bar code labels 71 on test tubes so they may be read by barcode reader 55 along cross-feed 95, and to insure that the test tubesmay pass under the armature 91 for ultrasonic liquid level sensor 90extending above cross-feed 95 so that the level of liquid in the testtubes is properly determined by the ultrasonic liquid level sensor 90.

A gross height sensor 320 may be optionally mounted to the side ofinfeed 80 behind panel 30 to detect test tubes that are not fully seatedbut pass under panel 30 or whether some test tubes are taller than thespecifications of instrument 10 permit it to handle. Gross height sensor320 comprises an optical infrared through-beam sensor 320 having atransmitter and receiver mounted on brackets 321, 322, respectively, andshould be calibrated to be sensitive enough to detect clear glass testtubes. Bracket 321 for the transmitter for gross height sensor 320 ismounted on one side of infeed 80 and bracket 322 for the receiver ismounted to the opposite side, both being mounted so that the transmitterand receiver detect test tubes positioned at a height slightly higherthan the tallest expected test tube with a cap to be placed in samplehandler 20 with tray 120 fully raised. If gross height sensor 320detects that a particular test tube in a rack is seated too high, themovement of the walking beam mechanism for infeed 80, which causes racks60 to move toward the rear of infeed 80, is stopped and the walking beammechanism is activated in the reverse direction (cam 220 causes tray 120to move back, up, forward, down) to move the rack with the improperlyseated test tube back into the operator-accessible from front area 81 ofinfeed 80 to enable the operator to reseat the test tube or to transfera sample in a test tube which is too tall for instrument 10 to a testtube which meets the specifications. An empty rack (which normally wouldbe filled with one or more test tubes) is shown in FIG. 3B in a positionafter it has passed panel 30 and gross height sensor 320.

The walking beam mechanism continues cycling and moving racks 60rearward to the back of infeed 80 until at least one of racks 60 reachesthe back of tray and the cycling of tray 120 lifts the rearmost rack 60in infeed 80 and transfers it onto a stationary track 336 that is formedaround the inside perimeter of cross-feed 95 (the distance separatingthe rear of infeed 80 from track 336 being preferably approximately 25mm) where cam 220 causes a rearward movement in a single cycle of 25 mm(FIGS. 1B and 6B). FIG. 3C shows the rack seated in cross-feed 95. Thistransfer to cross-feed 95 is detected by the left tab 110 of rack beingplaced on sensor 92 so as to block the infrared beam on optical sensor92. Once rack is moved to cross-feed 95, the walking beam mechanismcycles two additional times, which causes chamfered edges 157 on the toprear of tray 120 (FIG. 5B) to hit the front of tabs 110, 111 and therebypushes the rack rearward before catching the tabs 110, 111 on side walls151, 152 and again placing the rack on track 336. This insures that therack on track 336 of cross-feed 95 is perpendicular to cross-feed 95.The walking beam mechanism then turns off.

The walking beam mechanism will automatically stop sooner if a rack isnot deposited in cross-feed 95 after a certain amount of time, duringwhich the walking beam mechanism is cycled a maximum number of times.This would indicate that the movement of racks 60 has probably beenobstructed. In the embodiment where the walking beam mechanism movesracks 60 25 mm per cycle and tray 120 holds 21 racks each 23 mm wide,the cycling may be automatically stopped after a time sufficient for thewalking beam mechanism to cycle 25 times because only 21 cycles shouldhave been necessary to move a rack inserted at the front of tray 120 tocross-feed 95.

During the operation of the walking beam mechanism, the operator mayinsert additional racks 60 into infeed 80 even though tray 120 ismoving. The operator may also push racks 60 toward the rear of infeed 80as far as possible without disturbing the operation of sample handler20.

As explained above, in addition to detecting racks 60 in tray 120, rangesensor 280 also assists in detecting if a rack 60 is inserted intocross-feed 95 by tray 120 is skewed. Only limited skewing is possibledue to guide rails 130, 131 in tray 120 which transfers rack tocross-feed 95. However, a high degree of accuracy is required when arack is placed on cross-feed 95 because test tubes must be properlypositioned to be removed by a robotic arm (not shown). The properplacement of the left side of a rack into cross-feed 95 is detected byleft tab 110 on the rack being placed above sensor 92. At the same time,range sensor 280 detects if the right side of rack is skewed bycalculating that readings across range sensor 280 are within a smalllimited allowable range away from range sensor 280, the maximum limitpreferably being 0.1 inches. The rack is determined to be skewed if theright side of rack is further than this maximum limit.

Homing means, such as those known to those skilled in the art, should beprovided to accurately home the walking beam mechanism for infeed 80(and for outfeed 100).

Cross-Feed

Cross-feed 95 is designed to firmly grab racks 60 placed on track 336 ofcross-feed 95 by the walking beam mechanism of infeed 80, one rack at atime, to push the rack linearly to the opposite side of cross-feed 95behind outfeed 100, and to hold that rack downward and as vertically aspossible to both position each test tube in one of the eightpredetermined registration positions on cross-feed 95, which the roboticarm recognizes, to allow a robot to remove test tubes individually,without disturbing other test tubes in the rack 60, and withoutaccidentally pulling up the rack along with the test tube due tofriction between the test tube and the rack. Once the test tubes havebeen removed from the rack 60, outfeed 100 removes the rack fromcross-feed 95.

Referring to FIGS. 6A-6E, in addition to track 336, cross-feed 95 has afront wall 330, a rear wall 332 (or fence), a linear transport mechanism335 positioned under track 336 and a rack transport connectorsubassembly that comprises a platform 410 connected to the top of lineartransport mechanism 335 for gripping the rack on cross-feed 95. Frontwall 330 is short where it is situated behind infeed 80 and outfeed 100to provide clearance for a rack to be placed on cross-feed 95 by infeed80 and to be removed from cross-feed 95 by outfeed 100. The centerportion of front wall 330 that is not located behind infeed 80 oroutfeed 100 is taller and has a preloading means for providing a forceagainst the front of the rack as it moves through cross-feed 95 tomaintain the perpendicularity of the rack to track 334. However, thiscenter portion is lower than the level of openings 63 on rack to permitthe reading of bar code labels 70, 71. In one embodiment, the preloadingmeans comprises four pressure springs 336 on the back of front wall,each comprising a short metal link 337 parallel to front wall 330 and aspring 338 between each end of link 337 and mounting points 339 on frontwall 330. Rear wall 332 also helps properly seat the rack on cross-feed95 perpendicularly to track 336. Rear wall 332 is raised in the areabehind infeed 80 to prevent rack 60 from tilting backwards as it ispassed by tray 120, when tray 120 is a raised position, to cross-feed95.

The linear transport mechanism of cross-feed 95 comprises two pulleys340, 341, one pulley mounted to each end on a bottom 334 of lineartransport mechanism 335, and a belt 345 surrounding pulleys 340, 341.The linear transport mechanism is driven by a stepper motor 350, that ispreferably controlled by the microprocessor in the cross-feedcontroller, located beneath belt 345 behind the outfeed 100 side ofsample handler 20. Stepper motor 350 is electrically coupled to thecross-feed controller. The gear head output shaft 360 on motor 350 iscoupled to a pulley 370 which is in turn coupled to pulley 341 withdrive belt 380. A rail 390 is mounted along the top of assembly bottom334 on linear transport mechanism 335 and extends between pulleys 340,341. Two bearing blocks 400, 401, which may be any bearing block thatfits, slide along guide way 390 and are also attached to and move withbelt 334. A platform 410 is mounted to bearing blocks 400, 401.

Two L-shaped pusher fingers 94 a, 94 b are pivotally mounted at pivotpoints 427 to the top of platform 410 and each of fingers 94 a, 94 b ispreloaded with a spring 405 a, 405 b (FIG. 6H) to a raised position. Theupper ends of pusher fingers 94 a, 94 b are angled upward towards theoutfeed 100 side of cross-feed at an angle in the approximate range of20-45° to cam into windows 72, 74 on racks 60 and the top end 425 ofeach of fingers 94 a, 94 b is chamfered on both front and back sides tobias the rack against track 336. The back chamfer on fingers 94 a, 94 balso biases the rack 60 against rear wall 332 to ensure that the testtubes are properly in the registration locations for robot access.

A rack 60 may be placed in cross-feed 95 when platform 410 is positionedunder the arriving rack. In this case, with platform 410 in positionbehind infeed 80, pusher fingers 94 a, 94 b are in the raised positionand fit within openings 68, 69 without contacting windows 72, 74. Atother times, a rack 60 may be placed by tray 120 on cross-feed 95 whenplatform 410 is still holding another one of racks 60 behind outfeed 100or returning from the opposite side of cross-feed 95. In this case, asplatform 410 moves under the rack 60 behind infeed 80, pusher fingers 94a, 94 b are pivoted downward to the right by the force of the rack andthen return to the raised position as they arrive within openings 68,69.

Once a rack is placed securely on cross-feed 95, i.e. after it has beenplaced on cross-feed 95 and two additional 360 degree movements of cam220, platform 410 begins moving to the opposite side of cross-feed 95and, in the process, pusher fingers 94 a, 94 b cam within windows 72,74, respectively, to push the rack across track 336. The rack should notaccelerate to more than approximately 0.3 g to avoid spilling the liquidin open test tubes.

Bar code reader 55 is mounted adjacent cross-feed 95 a short distancebeyond the inner side of infeed 80 and reads bar code labels 70, 71 onthe rack and test tubes as rack and test tubes are transported alongcross-feed 95 in front of bar code reader 55. If a label cannot be read,such as when the bar code label on the test tube is not oriented towardbar code reader 55, the test tubes which were not identified are notextracted from the rack for processing by instrument 10 (or are sent tothe stat shuttle 600 for a second attempt at container identification).

An ultrasonic liquid level sensor 90 is positioned above cross-feed 95within a sensor holder 408 mounted to a bracket 91. (FIGS. 6E-6G) Thesensor 90 is preferably mounted in a gimbal 407 that fits within sensorholder 408. A preferred sensor 90 is height sensor (“transponder”)manufactured by Cosense as Model No. 123-10001. Sensor 90 should bepositioned on bracket 91 approximately 5 inches from the bottom of therack to allow for a 0.75 inch dead zone immediately beneath sensor 90.The data provided by sensor 90 may be used to provide a profile of thetype of test tubes in the rack, the level of liquid in open test tubes,and whether test tubes have a cap which must be removed. The rack isalso profiled to provide a height reference. This profiling is thesubject of the referenced application entitled Dynamic NoninvasiveDetection of Analytical Container Features Using Ultrasound. If theprofiling indicates that a cap is present, instrument 10 instructs arobotic arm to transport the capped test tubes to an automatic decapper,which is preferably a component on instrument 10 and may be included inthe sample handler module. After the decapper removes the cap, anotherultrasonic liquid level sensor (not shown) in the decapper determinesthe liquid level in the now uncapped test tube.

Ultrasonic liquid level sensor 90 is mounted upstream from bar codereader 55 along cross-feed 95 to provide the necessary distance for therack 60 on platform 410, which is initially at rest behind infeed 80, toaccelerate up to the slew speed that allows ultrasonic liquid levelsensor 90 to take a sufficient number of equally spaced data points andprofile the test tubes in the rack before passing under ultrasonicliquid level sensor 90. For example, in one embodiment, the requiredslew speed may be 2 inches/second so ultrasonic liquid level sensor 90must be placed far enough along cross-feed 95 to allow the rack 60 toreach that slew speed. Profiling requires a smooth motion of the rackand test tubes under sensor 90. Test tubes cannot accelerate too quicklyor samples in test tubes will be disturbed.

The data collected by ultrasonic liquid level sensor 90 is also used inconjunction with a homing sensor (not shown) for platform 410 built intothe linear transport mechanism of cross-feed 95 to verify that the rackis fully seated.

Track 336 of cross-feed 95 must maintain the perpendicularity of therack 60, to insure the accuracy of a critical datum point for the heightreference set by tabs 110, 111 on the rack as measured by the ultrasonicliquid level sensor 90 and to maintain the registration positions forthe robotic arm. Should sensor 90 malfunction, sample handler 20 couldstill be used but the test tubes would all have to be uncapped and befilled to substantially the same height.

As soon as the rack clears the area of cross-feed 95 behind infeed 80,if additional racks are in tray, they are detected by range sensor 280and the walking beam mechanism starts cycling again and continues movinguntil another rack is placed on track 336 of cross-feed 95.

When a rack reaches the opposite side of cross-feed 95, which is theunloading position shown in FIG. 3D for unloading test tubes from rackto be transported elsewhere in instrument 10, the right tab of rack ispositioned above sensor 93, which is an optical sensor similar to sensor92. A hard mechanical stop 440 is also provided at the outfeed end ofcross-feed 95 adjacent rail 390 to stop bearing blocks 400, 401 in aprecise position for unloading of the test tubes and subsequent transferof the rack 60 to outfeed 100. Hard stop 440 is adjustable toaccommodate some slight variations in the positioning of cross-feed 95in different instruments. After sensor 93 is triggered, softwareinstructs stepper motor 350 to advance 2 additional steps to tensionpusher fingers 94 a, 94 b to bias the rack against hard stop 440.

While in the unloading position, pusher fingers 94 a, 94 b remainengaged in windows 72, 74 and a robotic arm located on instrument 10above sample handler 20 may extract each of the test tubes from therack. The robotic arm is able to extract test tubes positioned incross-feed 95 as long as the test tubes are within one of theregistration locations. Allowance is made for some slight variation inposition. The engaged pusher fingers 94 a, 94 b mechanically constrainrack during extraction of the test tubes by robotic arm to preventfriction between the test tubes and rack from pulling the rack out ofcross-feed 95 along with the test tubes.

An optical through beam sensor (not shown) may be added to cross-feed 90to detect if there is a rack in the cross-feed during the initializationof instrument 10 after a power outage. Generally, this will not occur ifan uninterrupted power supply is attached to instrument 10 to allow anorderly power down, including moving racks 60 out of cross-feed, toinsure that no racks in cross-feed 95 remain undetected upon therestoration of power.

Outfeed

Referring to FIG. 3E, rack is moved to outfeed 100 after it has beenemptied of test tubes by the robotic arm. Like infeed 80, outfeed 100comprises a bidirectional walking beam mechanism mounted above thechassis 57 similar to the walking beam mechanism as described and shownin FIG. 4B above with reference to infeed 80 (except that cam 220′ has adifferent cam profile, a preferred profile being shown in FIG. 10B).Outfeed 100 has side walls 510, 511 which are joined together withcross-beams.

Outfeed 100 has a front area 101 which is always accessible to theoperation for removing racks from the system and a rear area 102 whichis inaccessible to the operator during operation of instrument 10. Theoperator is prevented from inserting a hand in rear area 102 by panel 40and door panel 45 (FIGS. 1 and 2) on instrument 10. A drip tray 590 isattached to the front of outfeed 100 to catch any spills.

Sitting within outfeed 100 is an outfeed tray 450 which has side walls505, 506 and a bottom 507 but is open at the front and rear of tray 450.(FIG. 7A and 7B) Tray 450 preferably holds a total of 20 racks with 10racks in rear area 102 and the remaining racks in front area 101. Likeinfeed tray 120, the top of side walls 505, 506 of outfeed tray 450extend farther back toward cross-feed 95 than the bottom of side walls505, 506, sloping forward along a middle section at the rear of sidewalls 505, 506 so that the bottom 507 of tray 450 does not hitcross-feed 95 when tray 450 rotates backward over cross-feed 95.

Tray 450 has a shoulder screw 460 attached to a U-shaped bracket 461 onthe bottom of tray 450 (FIG. 7C) which sits in a channel on slidingblock that is identical to sliding block 240 and causes the backwardsand forward movements of tray 450. Two guide rails 500, 501 extend fromthe front to back of the top of tray 450 but are asymmetricallypositioned across the width of the tray, with the same asymmetry as ininfeed tray 120, to accommodate and prevent skewing of racks 60. Tray450 is sufficiently wider than racks 60 to prevent camming of racksagainst side walls 505, 506. Outfeed tray 450 has a lip 580 in the back(FIG. 7B) and a drip tray 600 attached to the front of tray 450 forspill containment.

There are two primary differences between infeed 80 and outfeed 100. Thefirst difference is that the top of side walls 510, 511 on outfeed 100and top of side walls 505, 506 on outfeed tray in rear area 102 havetrapezoidal detents 531-539 (on outfeed side walls 510, 511) and detents540-549 (on tray side walls 505, 506). Tabs 110 on racks 60 may sit indetents 531-539 and 540-549 in order to precisely position each of racks60. This allows the robotic arm to locate the tube receptacles in racks60 to which the test tubes are to be returned using the predefined gridof 72 registration locations where test tubes may be inserted in outfeed100. The software tracks which of detent positions have racks and whichtube receptacle positions in those racks are available for the insertionof test tubes. In the embodiment illustrated in FIGS. 3D-3F, there arenine detents 530 on outfeed side walls 510, 511 and ten detents 531 onside walls 510, 511 of tray 450. When tray 450 is in its rest positionin outfeed 100, nine rear detents 540-548 in tray 450 are aligned withthe nine detents 531-539 on outfeed 100. Detents 531-539, 540-549 areidentical in shape and size. They are approximately 2 mm larger than thewidth of tabs 110 to provide a small amount of clearance for tabs 110.Thus, where detents 531-539, 540-549 are approximately 25 mm, tabs 110are made approximately 23 mm wide. While the precise distance that tray120 in infeed 80 must move rearward to translate racks 60 along infeed80 may vary, the distance which tray 450 must move must be precise, 25mm for the preferred specifications, to move racks 60 from one detent toanother.

Detents are separated by ridges 550 which maintain a separation betweenracks 60. Ridges 550 are designed to be high enough to maintain racks 60in the registration positions within the detents. The cam profile ofoutfeed 100 must be designed to lift racks 60 high enough and far enoughso as to clear ridges 550 when being moved between the detents.

If racks 60 are initially not centered within the detents as they aremoved within tray 450, the trapezoidal shape of detents pushes racks 60into the center of the detents. The trapezoidal shape of the detents and2 mm clearance also allows racks 60 to “float”, i.e., tilt slightlyforward or backward, when a robotic arm inserts a test tube in a tubereceptacle in the rack should the robotic arm or test tube be slightlyangled when the tube is inserted in the rack.

The second primary difference between infeed 80 and outfeed 100 is inthe cam profile. The outfeed cam causes outfeed tray 450 to be raisedand lowered a larger distance than infeed 80, the total distance betweenthe highest and lowest points being preferably 7½ mm. When tray 450 isfully lowered in outfeed 100, side walls 505, 506 sit 4 mm below sidewalls 510, 511. The cam raises tray 450 3½ mm, so as to lift tray 450above ridges 550 between detents.

Raising tray 450 higher in outfeed 100 does not create the same problemit would create in infeed 80 because the up and down movement of racks60 only occurs in the rear area 102 of tray 450, which is enclosedbehind panel 40 and therefore is less noisy and disturbing to theoperator than the movement of racks in infeed 80 where almost ⅔ of thetray is exposed to the operator.

Outfeed 100 both removes the rack, which has been emptied of test tubesfrom cross-feed 95 and moves racks 60 from one detent position to asecond adjacent detent position closer to the front of outfeed 100 togenerally output racks 60 toward the front of outfeed 100. As with thewalking beam mechanism on infeed 80, the movement of the walking beammechanism on outfeed 100 is accomplished by the rotation of tray 450 inconjunction with the transfer of tabs 110, 111 on rack between the topof side walls 510, 511 on outfeed 100 and the top of side walls 505, 506on tray 450.

To remove a rack 60 from cross-feed 95 after the test tubes have beenremoved from the rack 60 by the robotic arm, as tracked by the software,the motor on the outfeed walking beam mechanism is activated for apredetermined length of time to rotate the outfeed cam in acounterclockwise direction approximately a quarter of a turn. Thiscauses outfeed tray 450, in a continuous motion, to first move backwardapproximately 25 mm, which is the distance between two adjacent detents,such that the rearmost detent 540 is positioned under tabs 110, 111 andto thereby capture and cradle the rack between side walls 505, 506 oftray 450. At that point, the outfeed walking beam mechanism momentarilystops for a fixed time and holds tray 450 in a fixed position, whilepusher fingers 94 a, 94 b are extracted from windows 72, 74 on the rack60 in cross-feed 95, which has been emptied of test tubes, to allowplatform 410 to return to the opposite side of cross-feed 95 behindinfeed 80. As the platform 410 begins moving, the left side of pusherfingers 94 a, 94 b contact walls 79 a, 79 b and are thereby pusheddownward to move out from under the rack 60. By cradling the rack aspusher fingers 94 a, 94 b are extracted from windows, outfeed 100prevents the rack 60 from returning toward infeed 80 along cross-feed95. After the timeout for pusher fingers 94 a, 94 b to clear the rack,the rack 60 is captured within detent 540 on tray 450 and the outfeedwalking beam mechanism is again activated, causing tray 450 to move theextracted rack upward approximately 7½ mm, side walls 505, 506 of tray450 rising approximately 3½ mm above the top of side walls of outfeed100 and thereby transferring tabs on racks from the top of side walls510, 511 of outfeed 100 to the top of side walls 505, 506 of tray 450.Tray 450 then moves forward 25 mm and downward 7½ mm, transferring tabs110, 111 on racks 60 to side walls 510, 511 of outfeed 100, depositingthe rack removed from cross-feed 95 into rearmost detent position 531 onoutfeed 25 mm closer to the front of outfeed 100.

After removal of the first rack from cross-feed 95, the cycling of thewalking beam mechanism on outfeed 100 is repeated to remove other racks60 after they are emptied of test tubes in cross-feed 95. FIG. 3E showsa rack after it has been moved forward 3 detent positions and issuspended from detent 533. Tray 450 cannot rotate while a rack is incross-feed 95 behind outfeed 100 before the test tubes are removed fromthe rack 60 because the rack 60 must remain seated in platform 410during that time, but cycling resumes after the test tubes have beenextracted from that rack 60. As tray 450 picks up a rack 60 fromcross-feed 95, it also picks up any other racks 60 in the rear area 102of outfeed 100 and moves them towards the front of outfeed 100 onedetent position at a time. Detent positions 531-539 are generally filledwith racks 60 before the frontmost rack is output into theuser-accessible area of outfeed 100 when a tenth rack is picked up bytray 450.

Test tubes are output from other modules in instrument 10 afterprocessing and placed in the frontmost rack by robotic arm as they areoutput until that rack is full of test tubes. After the frontmost rackis filled, the remaining racks are filled with test tubes, with a rack60 that has an empty tube receptacle 63 and is closest to the front ofoutfeed 100 being filled first.

In the front area of tray 450, side walls 510, 511 have smooth top rimsand the top of side walls 505, 506 have an undercut 560 such that thetop of side walls 505, 506 of tray 450 in this front area are alwayslower than the side walls 510, 511 of outfeed 100, even when tray 450 isfully raised by the walking beam mechanism. This prevents tray 450 fromlifting and moving racks which are fed out into front area 101 of thetray. Racks 60 are output into this front area 101 may be manuallyremoved by the operator. If not immediately removed by the operator, thecurrently-outputted rack pushes and compacts the previously-outputtedracks in front area 101 along the smooth rims at the top of side walls510, 511 toward the operator. A sensor 595 at the front of tray detectsif tray 450 is filled with racks and turns off the motor for the walkingbeam mechanism on outfeed until some of racks 60 are removed. There isno front wall on tray 450 to make it easier to remove racks 60 by theoperator sliding one hand under several racks and simultaneously liftingthose racks with the other hand.

If a test tube which has been returned to the outfeed 100 is needed bythe operator immediately and the operator cannot wait until all ninedetent positions 531-539 are filled before the frontmost rack is output,sample handler 20 may be instructed by the operator with software at theuser interface of instrument 10 to output the frontmost rackimmediately. Upon receiving this instruction, sample handler 20 cyclesoutfeed 100 to move racks forward toward the front of instrument 10until the frontmost rack is output and then the walking beam mechanismis cycled backwards in the reverse direction to move racks 60 remainingin rear area 102 of outfeed 100 one at a time back toward cross-feed 95to their original positions. Undercut 560 on tray 450 prevents racks 60in front area 570 from being fed backwards into the rear area 102 duringthis reverse movement of racks back toward cross-feed 95.

As a result of moving some racks 60 with empty tube receptacles 66 outfrom outfeed rear area 102 to front area 101 for the operator toimmediately remove a test tube from a particular rack, there may not besufficient space in the remaining racks 60 in instrument 10 foroutputting all of the test tubes in instrument 10. To return sufficientracks 60 into sample handler 20, the operator may insert empty racks 60into infeed 80.

Several means are provided to prevent an operator from moving racks 60in rear area of outfeed 100 from their proper detent positions and awayfrom the registration locations specified in the software which wouldresult in problems with the robotic arm's placement of test tubes intoprecisely-positioned tube receptacles. A horizontal finger stop 502,i.e., a raised horizontal rail, extends horizontally from the bottom ofoutput tray 450 so the operator cannot, by tilting the bottom of a racktoward the back of outfeed 100 during removal of the rack, hit racks inrear area 102. Finger stop 502 rises high enough to block a tilted rackbut low enough so that it does not block the movement of rack forwardfrom rear area 102 to front area 570.

Also preventing operator interference are pneumatically-operated clamps310, 311 mounted to shafts 312, 313 respectively in respective clampingcylinders 314, 315. Air lines supply air to open and close clampingcylinders 314, 315. Whenever tray 450 is moving, and at most othertimes, shafts 312, 313 are raised above outfeed 100. However, whensoftware in instrument 10 determines that a rack is positioned in thefrontmost detent 539 on outfeed 100 as in FIG. 3F and tray 450 is notmoving, clamp cylinders 314, 315 will be pneumatically operated to pullclamps 310, 311 down into recesses 115, 116 in tabs 110, 111 on thisrack to hold it in this detent 539.

As mentioned above, door panel 45 is also situated above outfeed 100. Ifdoor panel 45 is opened by the operator while instrument 10 is operatingand the operator inserts a hand above rear area 102, an optical sensor570, comprising a transmitter mounted to bracket 571 to side wall 510and receiver mounted to bracket 570 to side wall 511, detects theintrusion and immediately stops instrument 10, including movement ofoutfeed 100 and the robotic arm, to prevent the operator from beinginjured by a moving walking beam or robotic arm. Thus, sensor 570operates as a “light curtain”.

Stat Shuttle

Sample handler 20 may also be provided with a stat shuttle 600 mountedparallel to and between infeed 80 and outfeed 100. (FIGS. 1A and 1B)Test tubes and other containers, may be fed into the instrument usingthe stat shuttle 600 to process these containers on a priority basis,with the instrument interrupting the normal operation of processingcontainers input via infeed 80. Stat shuttle 600 also enables thefeeding of other types of containers, such as reagent and diluentpackages, into the instrument on the stat shuttle 600. Stat shuttle 600may also be used to output containers from the instrument.

Referring to FIG. 9, stat shuttle 600 comprises a linear transportmechanism 610, similar to the linear transport mechanism for cross-feed95, coupled to a microprocessor-controlled stepper motor 615, such asmotor 350, via similar pulleys and drive belts. A platform (not shown)is connected to the linear transport mechanism 610 and an adapter 605,as described in the referenced application entitled Stat Shuttle Adapterand Transport Device, may be mounted to the platform. One of racks 60may be inserted into adapter 605 to transport test tubes into and out ofsample handler 20, either because one or more samples must be analyzedon a high priority or where infeed 80 is broken. Other adapters, such ascontainer-specific adapters like the reagent package and diluent packageadapters, may be inserted into adapter 605 to transport containers onstat shuttle 600. As with cross-feed 95, a bar code reader 623 (FIG. 1C)is placed alongside stat-shuttle 600 to read bar code labels on racks60, adapters, test tubes and other containers and an ultrasonic liquidlevel sensor 625 is positioned above the path of adapter 605 and ismounted in a bracket 635 adjacent the stat shuttle 600. Due to spaceconstraints, in a preferred embodiment, bar code reader 623 is notpositioned directly at containers in stat shuttle 600 but instead barcode reader 623 reads the bar codes as reflected by mirror 627positioned at a 45 degree angle between the right side and rear ofsample handler 20.

Containers, such as test tubes, may be inserted into stat shuttle 600 byan operator in a front area 600 a of stat shuttle 600 and stat shuttle600 transports the containers to a rear area 600 b of stat shuttle 600where a robotic arm may retrieve the containers from preferablypredefined registration positions. Similarly, the robotic arm may returnthe containers to one of the predefined registration positions on statshuttle 600 to output the containers.

Stat shuttle may also be used in a situation where reader 55 alongcross-feed 95 was unable to read the machine-readable code on the testtube or other container or sensor 90 was unable to obtain usable levelinformation from sensor 90. In this situation, the robotic arm maytransport the affected container to an awaiting rack in the rear area600 b of stat shuttle 600. Stat shuttle 600 may then output thecontainer to the front area 600 a of stat shuttle 600 and then move thecontainer back to rear area 600 b. The container thus has anotheropportunity to pass another reader 623 and sensor 625 to attempt toobtain usable data.

Laboratory Automation

Instrument 10 may be used as a subsystem in a laboratory automationsystem, such as the Lab Cell system from Bayer Corporation or theautomated apparatus described in U.S. Pat. No. 5,623,415, which isassigned to the SmithKline Beecham Corporation. When used in thismanner, test tubes are input into instrument from a transport line 700carrying test tubes adjacent instrument, such as to the left of samplehandler 20, rather than from racks 60 in infeed 80. (FIG. 1B). Testtubes in the transport line are individually held in packs which aremoved adjacent instrument 10 via diverter gates (not shown) and may berotated in a specified angular position in the pack. Test tubes areremoved from transport line 700 with the robotic arm and transported byrobotic arm to instrument 10 for processing.

As with test tubes input into instrument via racks 60, test tubes inputinto instrument 10 must be identified by a bar code reader 55 and anultrasonic level sensor 90 before being processed by instrument 10. Thetest tubes are therefore inserted into a lab automation adapter 710(FIG. 8A) that is attached to a modified platform (not shown) oncross-feed 95. Adapter 710 comprises an upper rack portion 512 that issimilar to racks 60. Upper rack portion 712 has tube receptacles 713separated by intermediate walls 714, each of tube receptacles 713 havinga base 711. Each tube receptacle 713 preferably also has a spring 717,such as a leaf spring, for holding the test tube in the respective tubereceptacle.

The adapter 710 has a cover 705, similar to the cover on racks 60. (FIG.8B) The top of cover 705 is positioned at the same height as the top ofone of racks 60 and the base 711 of each tube receptacle 713 is at thesame distance from the top of upper rack portion 712 as the base of tubereceptacles 63 when one of racks 60 is sitting on track 336. Thispositions the test tubes to allow bar code reader 55 and ultrasonicliquid level sensor 90 to function properly and positions the test tubesat the proper height for retrieval and placement of the test tubes by arobotic arm on instrument 10. Cover 705 has tabs 110′, 111′ that areused to provide the reference level for profiling of the rack withsensor 90. For similar reasons of detection and for placing of the testtubes in the same registration positions on cross-feed 95 for retrievalby the robotic arm, there are preferably a similar number of tubereceptacles 713 as there are tube receptacles 63 in racks 60 (in theillustrated embodiment, eight tube receptacles).

A front wall 715 of adapter 710 has openings 716 to permit bar codereader 55 to read machine identifiable code such as bar code labels onthe test tubes as well as a bar code label 718 on adapter 710. Thediverter gates in transport line 700 are used to angularly position eachtest tube so that the robotic arm inserts test tubes in adapter 710 withthe bar code labels positioned in openings 716.

Upper rack portion 712 is connected to a lower rack portion 720 that mayform a separate component to which upper rack portion 712 is removablymounted by any conventional means. Lower rack portion 720 has a mountingmeans 725, such as the illustrated bayonet, to mount adapter 710 to amount, such as a standard bayonet interlock mount (not shown), on themodified platform, which is preferably substantially the same platformas platform 410 plus the bayonet mount, on cross-feed 95. Thus, unlikeracks 60, adapter 710 is snapped in firmly to connector and cannot bepulled up by the robotic arm when test tubes are removed from adapter710. Mount 735 is positioned between pusher fingers 94 a, 94 b, whichare not used in this mode, and lower rack portion 720 does not come intocontact with or utilize the pusher fingers. The modified platform mayalways be used instead of platform 410 since the modification of theplatform does not interfere with the operation of pusher fingers 94 a,94 b.

When adapter 710 is connected to the modified platform, adapter 710converts cross-feed 95 to a bidirectional test tube shuttle to transporttest tubes removed from transport line along cross-feed 95 in front ofbar code reader 55 and under liquid level sensor 90 to the opposite sideof cross-feed 95 and may be used to transport test tubes outputted byother modules of instrument 10 back to transport line 700.

The modified platform also has an electrical sensor 740 to detect whenthe adapter 710 is connected to the modified platform so that softwaredisables the walking beam mechanisms of infeed 80 and outfeed 100.

Before outputting the test tubes back to transport line, the robotic armmay place the test tubes into a holding area 1000 (FIG. 1) to providethe instrument with an opportunity to perform reflex testing, i.e., totest the sample again if a particular value was obtained in the firsttest. After the tests are complete, the robotic arm transports andreinserts the test tubes back in the transport line 700. It ispreferable to include two robotic arms on instrument 10 where instrument10 will be used with a laboratory automation system to increase thethroughput instrument 10.

One skilled in the art will recognize that the present invention is notlimited to the above-described preferred embodiment, which is providedfor the purposes of illustration and not limitation. Modifications andvariations, in particular, to dimensions of components (e.g., size oftubes and racks), the number of components within a subassembly (e.g.,number of racks or tubes in a rack) and to the walking beam mechanisms,may be made to the above-described embodiment without departing from thespirit and scope of the invention.

We claim:
 1. A sample handler for an analytical instrument, said samplehandler handling a rack which holds a plurality of containers, said rackhaving a left side and a right side with tabs located thereon, said rackbeing transported within said sample handler, said sample handlercomprising: a feeder for feeding said rack comprising a first set ofside walls from which said rack is suspended by said tabs, a movabletray having a second set of side walls said tray being placed withinsaid feeder so that the first and second sets of side walls arevertically aligned, wherein said tray has guide rails which run parallelto each other along the longitudinal length of said tray to prevent saidrack from skewing in said tray; and a walking beam mechanism forsequentially moving said tray in an upward direction, a first lateraldirection, a downward direction and a second lateral direction, oppositesaid first lateral direction; whereby when said tray is moved in anupward direction the tabs of said rack are engaged and lifted by saidsecond side walls, disengaging the tabs from said first side walls. 2.The sample handler of claim 1 wherein said guide rails are placedasymmetrically between said second set of side walls.
 3. The samplehandler of claim 1 wherein said feeder is an infeed into which said rackis input.
 4. The sample handler of claim 3 wherein said infeed has afront and a rear and a range sensor is located behind said rear of saidinfeed to detect the inputting of said rack into said tray.
 5. Thesampler handler of claim 4 wherein said feeder is an outfeed whichoutputs said rack from said sampler handler.
 6. The sample handler ofclaim 5 wherein said outfeed and said tray have a front area and a reararea, and said first and second sets of side walls each have a top rimwhich in said rear area has at least two detents, in which said tabs onsaid rack may sit, separated by a ridge.
 7. The sample handler of claim6 wherein said detents on said first and second set of side walls have atrapezoidal shape.
 8. The sample handler of claim 7 wherein said ridgehas a length between said detents and said walking beam mechanism has acam having a profile that allows said tray to lift said rack above saidridge on said first set of side walls and move said rack from a first ofsaid detents on said first set of side walls to a second of saiddetents.
 9. The sample handler of claim 6 wherein said top rim of saidsecond set of side walls in said front area has an undercut and saidwalking beam mechanism for said outfeed has a cam that does not liftsaid top rim of second set of side walls in said front area above saidtop rim of said first set of side walls in said front area.
 10. Thesample handler of claim 8 wherein said front area of said tray isoperator-accessible and said tray has a finger stop extending between atleast a portion of said front and rear areas to minimize a possibilityof an operator from pushing said rack sitting in a frontmost of saidplurality of detents on said first or second sets of side wallsbackwards.
 11. The sample handler of claim 6 wherein said front area ofsaid tray is operator-accessible and said outfeed further comprisesclamps mounted to said first set of side walls adjacent said frontmostof said plurality of said detents on said first set of side walls tocoact with said tabs on said rack to hold said rack in said frontmostdetents in said first set of side walls to prevent an operator frompushing said rack backwards.
 12. The sample handler of claim 1 whereinsaid walking beam means operates in a bidirectional manner such that thefirst lateral direction is in a rearward direction toward the rear ofsaid feeder or in a forward direction toward the front of said feeder.